Board Thread:Pokémon Help/@comment-25235588-20180311115353/@comment-32358261-20180311120805

Everstone won’t increase the chances. This is only for breeding natures

Yes. Even if fainted and still in first slot, the effects still work.

The second Pokémon won’t matter at all. Still the first

Yes. Because the iv and nature would have to determined before the battle begins (because these factors can change how much damage it does, how much damage it can take and if it is faster or slower). So even if it faints mid battle, it would still have that higher chance of having the same ability